There is known a technology for setting an anchor bolts rigidly in a substrate structure such as a reinforced concrete block or a rock bed which comprises providing an encapsulated two-component adhesive system wherein one of the components is kept separate from the other component, drilling a hole in the substrate structure, setting the capsule in the hole and threading or driving an anchor bolt into the hole to thereby destroy the capsule for admixing the two components. In such a system, an accelerator is sometimes used to speed up the curing reaction.
As the adhesive agent for such a system, either an inorganic adhesive or an organic adhesive is employed but since inorganic adhesives generally are low in cure rate, organic adhesives are generally preferred. As to the curing component, one suited to the adhesive component is selectively employed.
In Japanese Patent Publication No. 38-12863, for instance, a synthetic resin adhesive such as a polyester, melamine or polyurethane adhesive is used as the adhesive component and a peroxide such as benzoyl peroxide is used as the curing component. Moreover, as an accelerator, dimethylaniline, cobalt naphthenate or the like is employed.
Japanese Patent Publication No. 48-41181 and Japanese Kokai Patent Publication No. 51-142810 disclose examples in which a polyester resin is used in combination with benzoyl peroxide.
Japanese Kokai Patent Publication No. 63-217037 shows examples employing a methacrylic resin-peroxide system. In Japanese Kokai Patent Publication No. 63-142200, No. 63-3154747 and No. 1-223300, an unsaturated polyester resin, methacrylic resin, epoxy-acrylate resin, or epoxy resin is used in combination with a peroxide, amine or acid anhydride.
Japanese Kokai Patent Publication No. 1-275681 mentions an unsaturated polyester resin, acrylic resin or vinyl ester resin as the adhesive component and a peroxide as the curing component.
Thus, for use in an anchor bolt-setting capsule, there have been proposed organic adhesive agents such as unsaturated polyester, acrylic, epoxy-acrylate, epoxy, melamine, vinyl ester and polyurethane resins as adhesive components and peroxides, amines and acid anhydrides as curing components. However, when these systems are applied to anchor bolts, the following problems are inevitable.
While these organic adhesive systems generally insure reduced cure times as compared with inorganic cements, the cure time typically is still as long as about 30 minutes at a temperature of 20.degree. C. and, as the ambient temperature falls, increases drastically to, for example, about 2 hours at 10.degree. C. and 8 to 24 hours at 0.degree. C.
In addition, depending on the pattern of fragmentation of the capsule, the contact between the adhesive component and the curing component is sometimes poor so that one cannot always expect that all the anchor bolts driven will be uniformly secured in position within a given time period. For insuring a uniform destruction of the capsule, it has also been proposed to adopt special capsule structures or special anchor bolt tip configurations but such practices not only impose limitations on usuable containers and anchor bolts but are self-limited in respect of reliability because anchoring operations are sometime carried out under poor field conditions.